Strain distribution in self-assembled InP/GaInP quantum dots

Abstract

Local strain on an atomic scale, as well as the size and the shape of InP quantum dots (QDs) embedded in GaInP, have been measured directly from high-resolution electron microscopy images. There is a strong spatial variation in strain within a QD. A large part of the misfit strain is distributed in the GaInP matrix surrounding the QDs, especially in the case of small spacing between the QD layers. The strain distribution varies significantly with the thickness of the GaInP spacer layers between QD layers. The compressive strain within the QDs decreases with decreasing spacing between the QD layers. This contributes to an increasing red shift of photoluminescence energy peak positions of QDs of multi-layers with decreasing thickness of the spacer layers between the QD layers in comparison with that of single layer QDs.